Hydatid Disease

Hydatid disease (echinococcosis) is a potentially serious illness caused by the cysts of a parasitic worm. You can get it from accidentally swallowing (ingesting) something contaminated with the parasite.

Echinococcosis (eck-EE-no-co-co-sis) causes cysts (liquid-filled growths) to develop in your organs. They most often form in your liver, but can also form in or spread to your:

• Brain
• Diaphragm
• Kidneys
• Lungs
• Spleen

After getting infected, the cysts usually don’t cause symptoms for months or years. As they grow, they can damage your organs and cause symptoms.

Hydatid disease happens all over the world. It’s less common in North America.

Types

There are several types of echinococcosis. They’re caused by different types of Echinococcus parasites. Types include:

• Cystic echinococcosis: This is the most common form. It can cause cysts in your liver, lungs or other organs. E. granulosus is the most common cause.
• Alveolar or multilocular echinococcosis: This form is rare but serious. The cysts look and behave like tumors, even though it’s not cancer. They make large, destructive masses, usually in your liver. They can move to other organs. E. multilocularis causes it.
• Polycystic or neotropical echinococcosis: This is the rarest form. It’s only found in South America. It’s similar to cystic echinococcosis, but its cysts have multiple parts (chambers). It usually affects your liver. E. vogeli and E. oligarthrus cause it.

Symptoms of hydatid disease

Echinococcosis usually doesn’t cause symptoms for months or even years. As the cysts grow or spread, they may cause:

• Fever
• Bloody stools
• Long-lasting cough
• Itchy skin
• Discomfort, pain or feeling of fullness in your belly or chest
• Hives or skin rash
• Jaundice (yellow skin)
• Lump or mass in your belly
• Nausea and vomiting
• Shortness of breath
• Unexplained weight loss

Hydatid disease causes

Echinococcus, a type of parasitic tapeworm, causes hydatid disease. It infects animals like dogs and foxes. The tapeworm eggs are released into the animal’s poop. You get echinococcosis by swallowing contaminated poop. This can happen by:

• Drinking contaminated water
• Eating contaminated vegetables, greens or berries
• Petting or handling an infected animal and then touching food or your mouth

Animals that carry Echinococcus tapeworms include:

• Bush dogs
• Dogs (wild and domestic)
• Foxes
• Raccoon dogs
• Wolves

These animals get it from eating the organs of other animals — like sheep, goats or pigs — that carry the parasite eggs. Humans don’t get it from sheep or other livestock directly.

Risk factors

Hydatid disease is more common in rural areas, where dogs may eat infected animals. You might have a higher risk of hydatid disease if you:

• Raise sheep or livestock and also have dogs
• Deworm or handle infected dogs
• Drink or eat in a space shared with infected dogs
• Slaughter your own sheep or other livestock

Complications

Echinococcosis can cause serious complications. Some cysts grow large and damage your organs. Alveolar echinococcosis can also spread from the original organ to others, like your spleen, lungs or brain. If a cyst ruptures, it can cause anaphylaxis, a severe allergic reaction.

How doctors diagnose echinococcosis

Healthcare providers can see echinococcosis cysts with medical imaging, like ultrasound, X-ray or CT scan. Other tests they might use for diagnosis include:

• Blood tests to look for antibodies to Echinococcus
• Fine needle aspiration (biopsy)
• PET scan (usually to monitor alveolar echinococcosis)

How is hydatid disease treated?

Treatment for hydatid disease depends on the size and location of the cysts. The most common treatments include:

• Medication: Most treatment plans include antiparasitic drugs like albendazole. If you have a small cyst, it might be the only treatment you need. Or your provider might recommend combining it with other treatments.
• PAIR (puncture, aspiration, injection, re-aspiration): PAIR is a procedure providers use to treat larger cysts. A provider uses a needle or catheter to make a hole in (puncture) and drain (aspirate) the cyst. Then, they inject a parasite-fighting solution into the cyst. Finally, they drain the cyst again (re-aspiration). This can be repeated until the cyst is completely emptied.
• Surgery: Removing the entire cyst can cure hydatid disease. Surgery is the primary treatment for alveolar echinococcosis. Your provider might also recommend surgery for larger cysts and cysts in your lungs or brain.

When should I see my healthcare provider?

If you have symptoms of hydatid disease, see your healthcare provider right away. Let them know if you have risk factors for echinococcosis, like being around livestock and dogs. This includes risk factors that you might have had years ago, since symptoms can take a long time to develop.

What is the prognosis for hydatid disease?

Early diagnosis and treatment give you the best chance of a good outcome. The most common kind, cystic echinococcosis, can often be cured by removing the cyst or treatment with antiparasitic medications. A small percentage (about 1% to 2%) of cases are fatal.

Alveolar echinococcosis can be harder to treat. It’s often diagnosed at a later stage. It can come back, even after treatment. But antiparasitic medications can manage it long-term. Without treatment, or if treatment isn’t effective, it can be fatal within 10 to 15 years of diagnosis.

Can hydatid disease be prevented?

In some parts of the world, sheep can be vaccinated to prevent tapeworm infections. This ultimately reduces the risk of dog and human infections. Other prevention strategies include:

• Have dogs regularly dewormed by a veterinarian.
• Avoid contact with animals that may be infected.
• Don’t slaughter sheep or other livestock at home.
• Don’t let dogs outside without supervision.
• Follow safe food handling guidelines.
• Wash your hands with soap and water frequently, especially before preparing food or after handling dogs.